Interrelationship of trabecular mechanical and microstructural properties

Noticeable changes in bone density are often first evident in trabecular bone. Moreover, qualities beyond density are important in identifying fracture risk. This study seeks to identify the degree to which the variability in trabecular material properties can be explained by using micro-CT (μCT) imaging. The material properties studied include stiffness, yield strength, and ultimate strength, while the μCT parameters analyzed include bone volume fraction, mean intercept length analysis, and degree of anisotropy. Trabecular bone was harvested from both the medial and lateral condyle of the left distal femur of 38 adult female sheep. The maximum correlation was found by combing all the μCT properties to explain approximately majority of the variability in modulus, yield, and ultimate strength (r²=0.87). In the principal loading direction, a lower amount of the variability in modulus is explained (r²=0.83), which is slightly less than the mediolateral direction but more than the anteroposterior direction. As the goal is to identify changes and potential fracture risk at the earliest possible time, the remaining variability should be identified. Further work with nano-indentation, fractals, and finite element modeling may yield the desired specificity.